Thermo-electric couple.



W. H. BRISTOL.

THERMO ELECTRIC COUPLE.

APPLICATION FILED APR.28, I915.

1 9 1 69,6 1 1 Patented Jan. 25, 1916.

M f [0% C}: (10 Q I 1 JO JVZFZZ A]. I I 6 44 140%)? Q INVENTOR NEY S PATENT Q WILLIAM H. BRISTOL, OF WATERIBURY, CONNECTICUT, ASSIG-NOR TO THE BRISTOL COMPANY, OF WATER/BURY, CONNECTICUT, A CORPORATION OF CONNECTICUT.

THERMO-ELECTRIC COUPLE.

Specification of Letters Patent.

Patented Jan. 25, 1916.

To all whom it may concern:

. Be it known that I, lViLLIAM H. BRISTOL, a citizen of the United States, and a resident of WVaterbury, in the county of New Haven and State of Connecticut, have invented certain new and useful Improvements in 'Thermo-Electric Couples, of which the foltions with the former secondary'couples whose thermo-electric effects are arranged to neutralize each other.

This patent discloses more particularly the use of expensive and high. resistance elements such as platinum and a platinum alloy for the'primary couple; and it is the object of the present invention to provide a compound couple of which also the primary portion shall be composed of comparatively inexpensive base metal elements and the extension portion of inexpensive base metal elements, generally of not particularly high melting point and of low resistance, whereby said latter elements need not be of large cross-section and will possess sufficient flexibility to be conveniently bent and carried considerable distances.

A further object of the invention is to combine such elements in a compound couple that a particularly high electro-motive force may be developed and of a comparatively straight line electro-motive force-tempera ture curve. Moreover, it will generally be desirable to have the elements of the pri-' mary couple of metals of comparatively high melting point, while the metals of the exten sion portion may be of a lower melting point, not, as a rule,'being exposed to extreme temperatures.

The drawing illustrates diagrammatically the improved compound couple.

As elements for the primary'couples various metals, or alloys, aresuitable, for example-nickel, tungsten, nickel-chromium, nickel-aluminum, etc. A combination that is particularly suitable for the primary couple is that set forth in U. S. Patent No.

971,767, the same consisting of a nickel chromium alloy (10% Cr.) as one element and a nickel-aluminum alloy (aluminum approximately 2%) as the other element. Such couple will give a practically straight line electro-motive force-temperature curve to practically the working limit of the materials. As a very satisfactory extension portion of the couple, I employ, for example, as one element an alloy of copper with nickel, the latter metal in varying percentages of from 20% to 70% and as the other element either a pure metal or an alloy, for example, copper, iron, etc., the proportion of alloying metal being determined by the neutralizing efiect necessary. With the particular primary couple hereinbefore set forth and composed of elements of nickel with 10% of chromium and nickel with 2% of aluminum, I employ for, the extension portion, copper in combination with the nickel-chromium element and copper with approximately 40% of nickel in combinationwith the nickel aluminum element of the said. primary couple, as shown in the drawing. The compound couple composed of these elements has been foundto give very satisfactory results, an electro-motive force being developed which is four to five times that of a platinumrhodium couple. The junctions between the primary portion and extension portion of the couple, also, may be exposed to comparatively high temperatures without introducing errors of indication. The. fact "that the said extension portion consists of inexpensive and low resistance metal and possesses considerable flexibility, permits, moreover, of this portion of the couple being conveniently extended and to considerable distances, thereby carrying the cold end of the couple to some distant point where the temperature is substantially uniform or readily maintained so and thus obviates errors of indication from fluctuations of temperature at the cold end.

I claim 1. A compound thermo electrio couple consisting of. a primary portion, one part of which is an alloy containing nickel and a relatively small proportion of aluminum, and the other a nickel-chromium alloy; and an extension portion, one part of which is copper, the same being combined with the nickel-chromium part of the primary portion, and the other an alloy of copper and nickel and combinedwith the nickel-aluminum alloy of the said primary portion.

2. A compound thermoelectric couple consisting of a primary portion, one part of which is an alloy containing nickel and approximately tWo (2%) per cent. of aluminum, and the other an alloy containing nickel and approximately ten (10%) per cent. of chromium; and an extension portion, one part of which is copper, the same being combined With the nickel-chromium part of the primary portion, and the other an alloy containing copper and forty (40%) 1:

per cent. of nickel and combined with the nickel-aluminum alloy of the said primary portion.

Signed at New York, in the county of New York, and State of New York, this 27th day 15 of April, A. D. 1915.

WILLIAM H. BRISTOL, 

